Gone Icon Gone--simply disappeared

My circle-L icon has disappeared from my IL "home"page and a few places elsewhere. I think I accidentally hit some key on the keyboard while typing a reply, that deleted it. Is there any way of getting it back? Please and thank you.

Um, I think that’s happened to me too?

So I researched this a bit, by going to the Discourse website, and reading the topics on discourse meta. Apparently, according to posts there, what disappears are the “default avatars” (the circled letters), but not the custom avatars. That seems to be the case here too.

The fix recommended there is to reboot the Discourse system, so there we have it, for now.